I honestly don't even understand why Mozilla did not add any special page on the official Firefox portal, for the 64 bits version!
Why so...? don't know. 64 bits architectures are'nt so new, and above all, 64 bits operating systems are coming down...!
The point is that you have to use Google (still or former Mozilla's friend...? anyway) to find a piece of information about Mozilla 64bits.
Well, here is the website I've found: http://www.mozilla-x86-64.com/
It appears that Firefox 64 bits is not being named... Firefox, but Shiretoko. Why not... after all the marketing campaign around Firebird, then Firefox... anyway.
Ah I should mention that I dared to take the risk to install Firefox and Shiretoko on the same system. It does work!
Each one reads the central configuration.
Though, there is still a problem with the extensions. If you like FiIrefox extensions, or even you think they're essential, there may come a problem: compatibility!
But whithout being to much specific, let's talk about a very common extension, that most of the "modern" websites (I don't like that point of view) use: Flash Player!
And the thing is, I'm still looking for a way to install Flash for Shiretoko on Windows 7 64bits... weeks after I started my tests.
Here is what comes if you go to the adobe website:
Okay you're gonna tell me: just go ahead and install it...
Well, even if I start Shiretoko with admin privileges, it is not the first time I come to this screen, and the installation simply does not work...
What a good web experience without Flash...!
Explication is there: http://kb2.adobe.com/cps/000/6b3af6c9.html
Okay this is not really Mozilla's fault, but at least, they could warn the user that the Flash extension is neither supported, nor supposed to work...
And you know what? Flash for 64bits Windows is not yet available, even in a beta version, while 64bits linux is already there! unbeleivable...
Then let's come back to the main subject: addons in general.
Users should be warned that they will have to check the Shiretoko compatibility for each addon, one by one...
By default, addon compatibility will be disabled. I recommend to use Addon Compatibility Reporter, and test each one by activating it.
You'll probably have suprises, since most of the addons you use everyday in the x86 version, will be marked as "not compatible". Just force the activation, and test.
Once again, this is more like a big beta test, than an real official version of one of the world's most-used browsers!